Compositions and methods for treating pain

ABSTRACT

In the present invention, Applicants demonstrate the effect of a biomembrane sealing agent on the development of chronic pain following tissue injury as well as acute pain in a model of acute inflammation. Applicants demonstrate the ability of this class of agents referred to as “biomembrane sealing agents” to reduce the severity of hyperalgesia and allodynia following mechanical insult to the nervous system as well as their ability to reduce acute pain in a model of acute inflammation. Applicant describes the use of injectable or depot formulations of biomembrane sealing agent(s) for prophylactic treatment such as they could be administered after the insult (i.e. post-injury or post-surgery) but before the onset of acute or chronic pain. Alternatively, biomembrane sealing agents could be used to reduce the severity of acute or chronic pain after onset.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of provisional application No.60/685,831, filed on May 31, 2005, which is incorporated herein byreference.

FIELD OF THE INVENTION

This invention relates to methods and compositions of treatingconditions associated with acute or chronic pain.

BACKGROUND

Pain is associated with a myriad of medical conditions and affectsmillions of Americans. As reported by the American Pain Foundation, over50 million Americans suffer from chronic pain including 20% ofindividual aged 60 and over who are affected by joint (arthritis orother disorders) and back pain. Furthermore, nearly 25 millionsAmericans experience acute pain due to injuries or surgical procedureseach year. The cost involved in the management of pain has beenestimated at $100 billion each year. In addition to its economicalburden, pain has a tremendous effect on the quality of life of affectedindividuals and is one of the most common causes of disability.

Accordingly, improved methods and compositions of treating acute andchronic pain are desired to alleviate these debilitating conditions.

Conditions affecting cardiovascular functions and blood flow haveincreased substantially in countries of central and eastern Europe andremains the major cause of premature death in Western populations. Forexample, atherosclerosis which involves formation of depots or plaqueinto arteries, caused almost 1 million deaths in 1992—twice as many asfrom cancer and 10 times as many as from accidents. Despite significantmedical advances, coronary artery disease (which results fromatherosclerosis and causes heart attacks) and atherosclerotic stroke areresponsible for more deaths than all other causes combined.

Accordingly, there is an urgent need for improved methods andcompositions for treating conditions affecting cardiovascular elementsand blood flow.

SUMMARY OF THE INVENTION

The current invention fulfills this and other foregoing needs byproviding devices, methods, and compositions useful for treating orpreventing pain consisting of at least one biomembrane sealing agent.

In addition, improved methods and compositions of treating damagedcardiovascular elements are desired.

The instant invention fulfills this and the other foregoing needs byproviding improved compositions and methods for treatment of conditionsassociated with acute and chronic pain as well as conditions associatedwith damaged cardiovascular elements and impaired blood flow.

In one aspect, the present invention provides a composition for treatinga pathological condition associated with acute or chronic pain as wellas damaged cardiovascular elements comprising at least one biomembranesealing agent. In one embodiment, the at least one biomembrane sealingagent is delivered in an injectable formulation. In another embodiment,the at least one biomembrane sealing agent comprises more than 10% ofthe injectable formulation. In another embodiment of the invention, thecomposition is incapable of forming a gel.

In different embodiments of the invention, the at least one biomembranesealing agent is selected from the group consisting of polyoxyethylenes,polyalkylene glycol, poly(ethylene glycol) or PEG, polyvinyl alcohol,pluronics, poloxamers, methyl cellulose, sodium carboxylmethylcellulose, hydroxyethyl starch, polyvinyl pyrrolidine, dextrans,poloxamer P-188, poly(polyethylene glycol methacryalte), poly(glycerolmethacrylate), poly(glycerol acrylatete), poly(polyethylene glycolacrylate), poly(alkyl oxazoline), phosphoryl choline polymers, sodiumand potassium polymethacrylate, sodium and potassium polyacrylate,polymethacrylatic acid and polyacrylic acid and any combinationsthereof.

In yet another aspect, the invention provides a method of treating apathological condition associated with pain or damaged cardiovascularelements, the method comprising delivering to a subject in need thereofa therapeutically effective amount of at least one biomembrane sealingagent, In one embodiment, the at least one biomembrane sealing agent isdelivered in an injectable formulation. In another embodiment, the atleast one biomembrane sealing agent comprises more than 10% of theinjectable formulation. In one embodiment of the invention, thecomposition is incapable of forming a gel.

In yet another aspect, the invention provides that a biomembrane sealingagent, such as, for example, PEG, may also potentiate the beneficialeffects of bioactive agents. In different embodiments, such bioactiveagents include, neurotransmitter and receptor modulators,anti-inflammatory agents, antioxidants, anti-apoptotic agents, nootropicand growth agents; modulators of lipid formation and transport,antiplatelet and anticoagulant agents, antineoplastic agents and agentsthat interfere with cellular division, blood flow modulators and anycombinations thereof.

Further, in different embodiments, the at least one biomembrane sealingagent and the at least one bioactive agent may be delivered by a methodselected from the group consisting of an intravenous administration, anintramuscular administration, an intrathecal administration, asubcutaneous administration, an intra-articular administration, anepidural administration, a parenteral administration, a directapplication onto a site of the pathological condition, an implanteddepot, and any combinations thereof. Certain aspects of the presentinvention provides for modes of vascular delivery such as perivascular,transvascular or catheter local delivery using applicable cathetercontrolled from a stent.

Preferably, biomembrane sealing agent(s) can be used to treat variousclinical conditions showing a chronic pain component including metabolicneuropathies such as diabetic and alcoholic neuropathies, postherapeuticneuralgia, Complex Regional Pain Syndrome and other pain syndromesderived from trauma to the central nervous system such as stroke,traumatic brain or spinal cord injury, pain derived from mechanical orbiochemical neuronal insults such as sciatica, carpal tunnel syndrome,phantom limb pain and pain associated with degenerative conditions suchas multiple sclerosis, arthritis and other joint diseases.

Another aspect of the present invention provides for treatment of acutepain associated with damaged or inflamed tissue derived from a traumaticinsult or derived from surgical and invasive therapeutic interventions.

Certain aspects of the present invention provide for treatment ofcardiovascular indications, such as for example, atheroscleroticlesions, vulnerable plaque, and acute myocardial infarct.

One aspect of the present invention provides for biosealing of theatherosclerotic lesions. This aspect of the present invention may alsoprovides for a combination of a biosealing agent and anti-inflammatoryagent.

Another aspect of the present invention provides for biosealing of theplaque area to reduce thrombogenicity (platelets deposition).

Another aspect of the present invention provides for biosealing duringand after aMI to reduce injury and oxidation related damage.

In one aspect, the invention provides a composition useful for treatingor preventing pain consisting of at least one biomembrane sealing agent,wherein the at least one biomembrane sealing agent is selected from thegroup consisting of poly(ethylene glycol), a block copolymer containinga polyalkylene glycol, triblock containing a polyalkylene glycol, ablock copolymer containing a polyalkylene oxide, triblock containing apolyalkylene oxide, polyvinyl alcohol, polyvinyl pyrrolidone, dextrans,poloxamine, pluronic polyols, dimethylsulfoxide, hydroxyethylstarch,sodium carboxymethyl cellulose, poly(polyethylene glycol methacryalte),poly(glycerol methacrylate), poly(glycerol acrylatete),poly(polyethylene glycol acrylate), poly(alkyl oxazoline), phosphorylcholine polymers, sodium and potassium polymethacrylate, sodium andpotassium polyacrylate, polymethacrylatic acid and polyacrylic acid andcombinations thereof.

In one embodiment of the invention, the at least one biomembrane sealingagent is poly(ethylene glycol).

In another aspect, the invention provides a composition of useful fortreating or preventing pain consisting of at least one biomembranesealing agent, wherein the at least one biomembrane sealing agent ispoly(ethylene glycol) having a molecular weight of between about 1,400and about 20,000 Da.

In one embodiment of the invention, the at least one biomembrane sealingagent has a linear or muti-arm structure.

In another aspect, the invention provides a method for treating orpreventing pain comprising administering to a subject an effectiveamount of at least one biomembrane sealing agent(s) by parenteraladministration, intravenous, subcutaneous, intramuscular,intra-articular, intrathecal and epidural administration.

In another aspect, the invention provides a method of preventing pain ina subject comprising administering post-injury, concurrently or aftersurgery or therapeutic intervention, but before the onset of acute orchronic pain, an effective amount of at least one biomembrane sealingagent.

In another aspect, the invention provides a method for reducing theseverity of the symptoms after onset of acute or chronic pain in asubject comprising administering to a subject suffering from the onsetof pain an effective amount of a biomembrane sealing agent(s) byparenteral administration, intravenous, subcutaneous, intramuscular,intra-articular, intrathecal and epidural administration.

In one aspect, the invention provides a method for reducing the severityof the symptoms after onset of chronic pain in a subject, wherein thesubject is suffering from diabetic neuropathy, alcoholic neuropathies,postherapeutic neuralgia, Complex Regional Pain Syndrome, stroke,traumatic brain injury, spinal cord injury, sciatica, carpal tunnelsyndrome, phantom limb pain, multiple sclerosis, arthritis and otherjoint diseases

In one aspect, the invention provides a method for reducing the severityof the symptoms after onset of acute pain derived from a traumaticinsult or derived from surgical and invasive therapeutic interventions.

In one aspect, the invention provides a composition for treating orpreventing pain consisting essentially of at least one biomembranesealing agent.

In one embodiment, the invention provides a composition for treating orpreventing pain consisting essentially of at least one biomembranesealing agent, wherein the at least one biomembrane sealing agent ispolyethylene glycol.

In another embodiment, the invention provides a composition for treatingor preventing pain consisting essentially of at least one biomembranesealing agent, wherein at least two biomembrane sealing agents areadministered.

In another embodiment, the invention provides a composition for treatingor preventing pain consisting essentially of at least one biomembranesealing agent, wherein said at least two biomembrane sealing agents areadministered simultaneously or sequentially.

In another embodiment, the invention provides a composition for treatingor preventing pain consisting essentially of at least one biomembranesealing agent, wherein the administration is repeated.

DETAILED DESCRIPTION

In the present invention, the applicants describe the effect of abiomembrane sealing agent, poly(ethylene glycol), on the development ofchronic pain following tissue injury as well as acute pain in a model ofacute inflammation. The applicants demonstrated the ability of thisclass of agents referred to as “biomembrane sealing agents” to reducethe severity of hyperalgesia and/or allodynia following mechanical andchemical tissue injuries. The applicants show the ability of abiomembrane sealing agent to accumulate on the walls of damaged bloodvessels and help restoring normal blood flow and mean arterial pressurein injured animals. The applicants describe the use of injectableformulations of biomembrane sealing agent(s) for prophylactic treatmentsuch as they could be administered concurrently to an invasivetherapeutic intervention or after the insult (i.e. post-injury orpost-surgery) but before the onset of acute or chronic pain orcardiovascular disease. Alternatively, biomembrane sealing agents couldbe used to reduce the severity of symptomatic pathological pain andcardiovascular disease after onset.

To aid in the understanding of the invention, the following non-limitingdefinitions are provided:

The term “treating” or “treatment” of a disease refers to executing aprotocol, which may include administering one or more drugs to a patient(human or otherwise), in an effort to alleviate signs or symptoms of thedisease. Alleviation can occur prior to signs or symptoms of the diseaseappearing, as well as after their appearance. Thus, “treating” or“treatment” includes “preventing” or “prevention” of disease. Inaddition, “treating” or “treatment” does not require completealleviation of signs or symptoms, does not require a cure, andspecifically includes protocols which have only a marginal effect on thepatient.

The term “subject” includes a living or cultured system upon which themethods and/or kits of the current invention is used. The term includes,without limitation, humans.

The term “practitioner” means a person who practices methods, kits, andcompositions of the instant invention on the subject. The term includes,without limitations, doctors, other medical personnel, and researchers.

Allodynia and hyperalgesia are terms used to define pain symptoms andthe extent of the body region affected by pain.

Accordingly, the term “allodynia” refers to pain resulting from astimulus that ordinarily does not elicit a painful response.

The term “hyperalgesia” refers to an increased sensitivity to a normallypainful stimulus. Primary hyperalgesia affects the immediate area of theinjury.

The term “acute pain” refers to pain resulting from an acute event andgenerally decreasing in intensity over a period of a few days to a fewweeks.

The term “chronic pain” refers to pain resulting from an acute orrepeated events and generally increasing in intensity over a period of afew weeks to years.

The term “damaged” refers to a condition derived from acute orrepetitive insults including without limitation, mechanical, chemicaland biological insults such as inflammation and pathological depositionof biological materials and free radicals.

The term “cardiovascular elements” refer to the heart and blood vesselsincluding arteries, veins and capillaries.

The term “bioactive agent” refers to chemical compounds and biologicalcompounds including protein, peptide, polypeptide, antibody, antibodyfragment, DNA, RNA and cell.

All references to chemical compounds, including without limitation,biomembrane sealing agents, markers, and bioactive agents include allforms of these chemical compounds (i.e., salts, esters, hydrates,ethanolates, etc.), wherein said forms possess at least partialactivities of the respective chemical compounds.

Acute and Chronic Pain Indications

There are two basic forms of physical pain: acute and chronic. Acutepain, for the most part, results from disease, inflammation, or injuryto tissues. It is mediated by activation of sensory fibers also known asnociceptive neurons. Nociceptive pain normally disappears after healing,for example in cases of post-traumatic or post-operative pain.Unfortunately, in some individuals, pathological changes occur thatincrease the sensitivity of the sensory neurons. In those cases,symptomatic pain can become chronic and persists for months or evenyears after the initial insult.

Acute insults of mechanical, chemical or biological nature can triggerthe development of chronic pain. It may also derive from various chronicconditions linked to persistent on-going tissue damage due, for example,to chronic inflammatory reactions or autoimmune diseases.

Pain and the extent of the area affected by pain can be defined by themeasure of allodynia and hyperalgesia. Allodynia is defined as painresulting from a stimulus that ordinarily does not elicit a painfulresponse. Hyperalgesia is defined as an increased sensitivity to anormally painful stimulus. Primary hyperalgesia affects the immediatearea of the injury. The term secondary hyperalgesia or referred pain isnormally utilized in cases when sensitization has extended to a broaderarea surrounding the injury.

There are two main modalities of pain: visceral for internal organs andsomatic for peripheral tissues. Somatic sensations are relayed from theperiphery to the central nervous system by the A and C sensory fiberswhich have their nucleus in the dorsal root ganglia lining the spine. Atone extremity, these neurons have receptors, called “nociceptors”,buried in tissues that can respond to various stimuli includingpressure, temperature and pH. These fibers act as transducers,converting stimuli into nociceptive impulses that are promptlytransmitted to the projection neurons located in the spinal cord. Theseprojections neurons will then transmit the sensory signals to the brainvia brainstem, thalamic and other supraspinal structures before thesignals finally reach the corticocerebral sensory areas.

The perception and relay of painful sensations carried by neuronalfibers can be modulated at various levels including peripheral endings,intermediate levels such as in the spinal cord, brainstem, thalamic andother supraspinal structures or even in the cerebral cortex. Increasedsensory information and translation to pain can be achieved by directmechanisms such as increased number of sensory endings and expressionand/or increased sensitivity of their receptors. Relay of the sensoryinformation to the brain can also be regulated directly or indirectly byinterneurons, ascending and/or descending neuronal fibers. Inflammation,disturbance of blood flow and/or changes in the characteristics of theblood-CNS-barrier can influence the occurrence and/or severity of acuteand chronic pain.

Clinically, these changes may manifest as an increased response to anoxious stimulus (hyperalgesia), a painful response to a normallyinnocuous stimulus (allodynia), prolonged pain after a transientstimulus (persistent pain), and/or the spread of pain to uninjuredtissue (i.e., referred pain).

Chronic pain etiologies include radiculopathy, plexopathy, peripheralnerve lesion, Complex Regional Pain Syndrome and central pain. Examplesof clinical conditions associated with chronic pain include metabolicneuropathies such as diabetic and alcoholic neuropathies, postherapeuticneuralgia, pain syndromes derived from trauma to the central nervoussystem such as stroke, traumatic brain, spinal cord or caudal equineinjuries, pain derived from mechanical or biochemical neuronal insultssuch as sciatica, carpal tunnel syndrome, phantom limb pain andsymptomatic pain associated with degenerative conditions such asmultiple sclerosis, arthritis and other joint diseases.

Additional clinical conditions would include acute or chronicsymptomatic pain derived from surgical or other invasive interventionsas well as acute or chronic pain derived from injury of peripheralneuronal or non-neuronal tissues.

Inflammation is the body's normal protective response to conditions thatinclude a tissue necrosis component. Tissue necrosis can be derived froma mechanical, chemical, biological or biochemical insult. Clinicalconditions with an inflammatory component include traumatic tissueinjury, surgery, invasive therapeutic intervention, degenerativediseases such as arthritis and other joint diseases as well asirritation, hypersensitivity, and auto-immune reactions.

During this natural “defense” process, local increases in blood flow andcapillary permeability lead to accumulation of fluid, proteins andimmune cells in the inflamed area. Some of these cells can releasechemical mediators of inflammation including histamine, cytokines,bradykinin and prostaglandins that can attract more immune cells at thesite of inflammation and/or increase the sensitivity of pain fiberswithin the affected area. As the body mounts this protective response,the symptoms of inflammation develop. These symptoms include, withoutlimitation, pain, swelling and increased warmth and redness of the skin.The inflammatory response has to be tightly regulated otherwise it maylead to tissue necrosis and development of acute and chronic painconditions.

Exemplary pro-inflammatory molecules include cytokines, chemokines,neuropeptides, bradykinin, histamine and prostaglandins. Suitable activeingredients may include steroids, nonsteroidal anti-inflammatory drugs,COX inhibitors, modulators of TNF-alpha or IL-1 cytokine levels orreceptors.

It appears that there is no direct and positive correlation betweenincreased or the level of preserved neuronal activity after tissueinjury and decreased incidence of chronic pain development. To thecontrary, studies have reported an inverse association between theseverity of neuronal insults and the development of chronic painsyndromes. For example, posttraumatic headaches are more common in mildcases of brain injury as compared to severe and moderate cases of braininjury. Similarly, in the population affected by spine injury, anincreased risk of developing chronic pain has been associated withmilder conditions relative to more severely impaired cases (Nepomucenoet al., 1979, Davidoff et al., 1987: Demirel et al., 1998). In thosestudies, the incidence of the development of chronic pain was higher inparaplegic versus tetraplegic patients, and in patients with incompleteversus those with complete spinal cord lesions. Furthermore, it appearsthat within the complete population, only individuals with somemeasurable transmission across the spinal lesion may experience painbelow the injury whereas a majority of patients without pain had noresidual neuronal function below the site of lesion (Beric, 1997). Inthose conditions, a therapy that can increase recovery of neuronalactivity following direct or indirect injury to the nervous system wouldnot be indicative of a potential reduction in the occurrence or severityof pathological pain in those patients.

Patients with symptomatic pain from a broad range of etiologies areaffected by acute or chronic allodynia and hyperalgesia. Specificscoring systems have been developed to monitor changes in sensitivity topainful (hyperalgesia) or normally nonpainful (allodynia) stimuli. TheseQuantitative Sensory Tests (QST) are becoming the new method of choicein assessing evoked pain in patients with pain syndromes. QST have beenutilized to test various drugs for patients who developed acute orchronic pain symptoms following insults to central and/or peripheralneuronal components including SCI and stroke (Attal et al., 2000; Attalet al., 2002; Finnerup et al., 2005), surgeries or other invasivetreatments, injuries such as bone fractures, shingles and development ofpostherapeutic neuralgia (Leung et al., 2001), phantom limb pain andidiopathic neuropathy (Attal et al., 1998).

Scoring systems to monitor acute and chronic allodynia and hyperalgesiain animal models of tissue injury have been used extensively to studythe mechanisms involved in the sensation of pain and to test potentialtreatments. More recently, similar scoring systems have been applied topain syndromes that can be developed after injury to the central nervoussystem (Gris et al., 2004; Hao et al., 2004).

In both humans and animals, tissue injuries such as high thoracic andcervical spinal cord injury often result in hypotension or reduced meanarterial pressure at rest which reduces tissue perfusion and may impairfunctional recovery and orthostatic tolerance.

Autonomic dysreflexia is also a common and potentially life threateningcondition associated with spine injury, characterized by large increasesin blood pressure in response to a stimuli below the level of injury;most commonly bladder or bowel distension.

Biomembrane Sealing Agents

For more than 40 years, biomembrane sealing agents of various molecularweights have been utilized as adjuncts to culture media for theirability to protect cells against fluid-mechanical injuries. These agentsinclude hydrophilic polymers such as polyoxyethylenes, polyalkyleneglycol, polyethylene glycols (PEG), polyvinyl alcohol, amphipaticpolymers such as pluronics or poloxamers, including poloxamer P-188(also known as CRL-5861, available from CytRx Corp., Los Angeles,Calif.) (Michaels and Papoutsakis, 1991) as well as methyl cellulose(Kuchler et al., 1960), sodium carboxylmethyl cellulose, hydroxyethylstarch, polyvinyl pyrrolidine and dextrans (Mizrahi and Moore, 1970;Mizrahi, 1975; Mizrahi, 1983).

Some biomembrane sealing agents including hydroxyethyl starch (Badet etal., 2005) and PEG (Faure J.P., et al., (2002) Polyethylene glycolreduces early and long-term cold ischemia-reperfusion and renal medullainjury. J Pharmacol Exp Ther September;302(3):861-70; Hauet et al.,2001) have shown effective cryopreservative abilities in organtransplantation studies. Poloxamer P-188 and a neutral dextran protectedmuscle cells against electroporation or thermally driven cell membranepermeabilization (Lee et al., 1992). Direct application of PEG was shownto increase neuronal activity of transected or crushed axon (Bittner etal., 1986), peripheral nerve (Donaldson et al., 2002) and spinal cordpreparations in vitro (Lore et al., 1999; Shi et al., 1999; Shi andBorgens, 1999; Shi and Borgens, 2000; Luo et al., 2002) or in vivo(Borgens et al., 2002). Intravenous or subcutaneous administration ofPEG or Poloxamer P-188 increased the cutaneous trunchi muscle reflexresponse after experimental spinal cord contusion in guinea pigs(Borgens and Bohnert, 2001; Borgens et al., 2004) and increased neuronalactivity in a naturally occurring spinal cord injury model in dogs(Laverty et al., 2004). PEGs of various molecular weights from1,400-20000 Da, having a linear or multiple arms structure were shown toincrease neuronal activity following tissue injury (Hauet et al., 2001;Detloff et al., 2005; Shi et al., 1999).

Biomembrane sealing agents can be effective following different modes ofdelivery including local and prolonged cellular exposure, direct andshort-term tissue or organ exposure or systemic administration.Effective concentrations of biomembrane sealing agents may varydepending on the purpose and/or mode of delivery For example, about0.05% concentration is effective 1in tissue culture applications(Michaels and Papoutsakis, 1991) and about 30% to about 50%concentration is effective for organ preservation and upon in vivoadministration in animals (Hauet et al., 2001; Shi et al., 1999; Borgensand Bohnert, 2001; Borgens et al., 2004).

As mentioned earlier, it appears that there is no direct and positivecorrelation between increased or the level of preserved neuronalactivity after tissue injury and decreased incidence of chronic paindevelopment. For example, milder injuries have been associated withincreased incidence of chronic pain in SCI and TBI patients (Lahz andByrant, 1996; Uomoto and Esselman, 1993; Beetar et al., 1996; Nepomucenoet al., 1979, Davidoff et al., 1987: Demirel et al., 1998). Furthermore,it has been suggested that in SCI patients, a certain level of neuronalfunctions across the spinal lesion is a prerequisite for development ofchronic pain at level or below the lesion (Beric, 1997).

In clinical settings, the acute and sub-acute intervention in cases ofinjury to the nervous system is directed toward maintaining the patientalive in cases of life-threatening injury and to the preservation ofneuronal functions in general. In other words, the “state of care” willbe focusing on the amount of sensory, motor and cognitive functions thatare recovered following injury and during the rehabilitation program.Less emphasis will be applied to monitoring the occurrence ofpathological dysfunction in the newly recovered neuronal activity. Themain reason for that is probably that these pathological dysfunctions donot manifest clearly before most patients have left the rehabilitationcenter. For example, a majority of SCI clinical trials have used theASIA score to evaluate the effect of acute treatments or drugsdelivered. The ASIA score has been conceived to monitor sensory andmotor functions, but it does not address the development and/or severityof pathological pain syndromes. Similarly, the animal studies thatevaluated the effect of PEG in models of SCI focused on the recovery ofmotor and sensory functions in general, they did not address theoccurrence of pathological pain syndromes after injury (Borgens et al.,2002; Laverty et al., 2004). In the contrary, within their particularexperimental setting, a strong response (including aggressivebehavioral) to light touch, sharp pinch and/or forceful squeezing of theback on the animal, limbs or digit of the paws was considered as apositive response such as the strongest response was given the highestrecovery score. In these conditions, it would have been impossible todifferentiate between recovery of normal sensory functions anddevelopment of abnormal/pathological pain syndromes.

As described earlier, patients with neuropathic pain from a broad rangeof etiologies are affected by chronic allodynia and hyperalgesia.Recently, specific scoring systems have been developed and applied inclinical setting to monitor changes in sensitivity to painful(hyperalgesia) or normally nonpainful (allodynia) stimuli. TheseQuantitative Sensory Tests (QST) are becoming a method of choice inassessing evoked pain in patients with neuropathic pain syndromes. QSThave been utilized to test various drugs for patients who developedchronic pain symptoms following insults to central and/or peripheralneuronal components including spinal cord injury and stroke (Attal etal., 2002; Attal et al., 2000), surgeries or other invasive treatments,injuries such as bone fractures, shingles and development ofpostherapeutic neuralgia (Leung et al., 2001), phantom limb pain andidiopathic neuropathy (Attal et al., 1998). Scoring systems to monitorallodynia and hyperalgesia in animal models of peripheral injury orinflammation have been used extensively to study the mechanisms involvedin chronic pain development and to test potential treatments. Morerecently, similar scoring systems have been applied to pain syndromesthat can be developed after injury to the central nervous system (Griset al., 2004; Hao et al., 2004). Similar scoring system are also used tomeasure pain in acute animal models of inflammation.

Bioactive Agents

Suitable examples of antioxidants include, without limitation, freeradical scavengers and chelators enzymes, co-enzymes, spin-trap agents,ion and metal chelators, lipid peroxidation inhibitors such asflavinoids, N-tert-butyl-alpha-phenylnitrone, NXY-059, Edaravone,glutathione and derivates, and any combinations thereof.

Suitable anti-inflammatory compounds include the compounds of bothsteroidal and non-steroidal structures.

Suitable non-limiting examples of steroidal anti-inflammatory compoundsare corticosteroids such as hydrocortisone, cortisol,hydroxyltriamcinolone, alpha-methyl dexamethasone,dexamethasone-phosphate, beclomethasone dipropionates, clobetasolvalerate, desonide, desoxymethasone, desoxycorticosterone acetate,dexamethasone, dichlorisone, diflorasone diacetate, diflucortolonevalerate, fluadrenolone, fluclorolone acetonide, fludrocortisone,flumethasone pivalate, fluosinolone acetonide, fluocinonide, flucortinebutylesters, fluocortolone, fluprednidene(fluprednylidene) acetate,flurandrenolone, halcinonide, hydrocortisone acetate, hydrocortisonebutyrate, methylprednisolone, triamcinolone acetonide, cortisone,cortodoxone, flucetonide, fludrocortisone, difluorosone diacetate,fluradrenolone, fludrocortisone, diflurosone diacetate, fluocinolone,fluradrenolone acetonide, medrysone, amcinafel, amcinafide,betamethasone and the balance of its esters, chloroprednisone,chlorprednisone acetate, clocortelone, clescinolone, dichlorisone,diflurprednate, flucloronide, flunisolide, fluoromethalone, fluperolone,fluprednisolone, hydrocortisone valerate, hydrocortisonecyclopentylpropionate, hydrocortamate, meprednisone, paramethasone,prednisolone, prednisone, beclomethasone dipropionate, triamcinolone.Mixtures of the above steroidal anti-inflammatory compounds can also beused.

Non-limiting example of non-steroidal anti-inflammatory compoundsinclude nabumetone, celecoxib, etodolac, nimesulide, apasone, gold,oxicams, such as piroxicam, isoxicam, meloxicam, tenoxicam, sudoxicam,and CP-14,304; the salicylates, such as aspirin, disalcid, benorylate,trilisate, safapryn, solprin, diflunisal, and fendosal; the acetic acidderivatives, such as diclofenac, fenclofenac, indomethacin, sulindac,tolmetin, isoxepac, furofenac, tiopinac, zidometacin, acematacin,fentiazac, zomepirac, clindanac, oxepinac, felbinac, and ketorolac; thefenamates, such as mefenamic, meclofenamic, flufenamic, niflumic, andtolfenamic acids; the propionic acid derivatives, such as ibuprofen,naproxen, benoxaprofen, flurbiprofen, ketoprofen, fenoprofen, fenbufen,indopropfen, pirprofen, carprofen, oxaprozin, pranoprofen, miroprofen,tioxaprofen, suprofen, alminoprofen, and tiaprofenic; and the pyrazoles,such as phenylbutazone, oxyphenbutazone, feprazone, azapropazone, andtrimethazone.

The variety of compounds encompassed by the anti-inflammatory group ofagents are well-known to those skilled in the art. For detaileddisclosure of the chemical structure, synthesis, side effects, etc. ofnon-steroidal anti-inflammatory compounds, reference may be had tostandard texts, including Anti-inflammatory and Anti-Rheumatic Drugs, K.D. Rainsford, Vol. I-III, CRC Press, Boca Raton, (1985), andAnti-inflammatory Agents, Chemistry and Pharmacology 1, R. A. Scherrer,et al., Academic Press, New York (1974), each incorporated herein byreference.

Mixtures of these non-steroidal anti-inflammatory compounds may also beemployed, as well as the pharmologically acceptable salts and esters ofthese compounds.

In addition, so-called “natural” anti-inflammatory compounds are usefulin methods of the disclosed invention. Such compounds may suitably beobtained as an extract by suitable physical and/or chemical isolationfrom natural sources (e.g., plants, fungi, by-products ofmicroorganisms). Suitable non-limiting examples of such compoundsinclude candelilla wax, alpha bisabolol, aloe vera, Manjistha (extractedfrom plants in the genus Rubia, particularly Rubia Cordifolia), andGuggal (extracted from plants in the genus Commiphora, particularlyCommiphora Mukul), kola extract, chamomile, sea whip extract, compoundsof the Licorice (the plant genus/species Glycyrrhiza glabra) family,including glycyrrhetic acid, glycyrrhizic acid, and derivatives thereof(e.g., salts and esters). Suitable salts of the foregoing compoundsinclude metal and ammonium salts. Suitable esters include C₂-C₂₄saturated or unsaturated esters of the acids, preferably C₁₀-C₂₄, morepreferably C₁₆-C₂₄. Specific examples of the foregoing include oilsoluble licorice extract, the glycyrrhizic and glycyrrhetic acidsthemselves, monoammonium glycyrrhizinate, monopotassium glycyrrhizinate,dipotassium glycyrrhizinate, 1-beta-glycyrrhetic acid, stearylglycyrrhetinate, and 3-stearyloxy-glycyrrhetinic acid, and duodenum3-succinyloxy-beta-glycyrrhetinate.

Suitable examples of neurotransmitter and receptor modulators include,without limitations, glutamate receptor modulators, adenosine receptormodulators, acetylcholine receptor modulators, adrenaline receptormodulators, noradrenaline receptor modulators epinephrine receptormodulators and norepinephrine receptor modulators, cannabinoid receptorsmodulators, and any combinations thereof. A person of ordinary skill inthe art will appreciate that one of the receptor modulators is a ligandnaturally occurring in a subject's body. For example, glutamatereceptors modulators include glutamate.

In another embodiment, the at least one bioactive agent is a modulatorof glutamate transmission, such as(1S,2S)-1-(4-hydroxyphenyl)-2-(4-hydroxy-4-phenylpiperidino)-1-propanol(also known as CP-101,606), Riluzole (Rilutek®), Topiramate, Amantadine,Gacyclidine, BAY-38-7271, S-1749, YM872 and RPR117824.

In another embodiment, the at least one bioactive agent is a cannabinoidreceptor modulator such as dexanabinol (Pharmos Corporation, Iselin,N.J., USA).

Suitable examples of antiplatelet agents include, without limitationaspirin, dipyridamole, ticlopidine and abciximab and any combinationsthereof.

Suitable examples of anticoagulant sometime referred to as “bloodthinner” agents include, without limitation, heparin and Warfarin (brandname Coumadin®, Warfilone®) and any combinations thereof.

Suitable examples of antineoplastic agents or agents that can interferewith cellular division include, without limitation, vinca alkoloids,vinblastin, vincristine, Palifermin, Paclitaxel, Bleomycin, cytarabine,Vindesine, Pemetrexed, Estramustine, Daunorubicin, and Doxorubicin andany combinations thereof.

Anti-apoptotic agents include, without limitations, inhibitors ofpro-apoptotic signals (e.g., caspases, proteases, kinases, deathreceptors such as CD-095, modulators of cytochrome C release, inhibitorsof mitochondrial pore opening and swelling); modulators of cell cycle;anti-apoptotoc compounds (e.g., bcl-2); immunophilins includingcyclosporine A, minocycline and Rho kinase modulators, and anycombinations thereof. Suitable non-limiting examples of Rho pathwaymodulators include Cethrin, which is a modified bacterial C3 exoenzyme(available from BioAxone Therapeutics, Inc., Saint-Lauren, Quebec,Canada) and hexahydro-1-(5-isoquinolinylsulfonyl)-1H-1,4-diasepine (alsoknown as Fasudil, available from Asahi Kasei Corp., Tokio, Japan).

Nootropic and growth agents include, without limitation, growth factors;inosine, creatine, choline, CDP-choline, IGF, GDNF, AIT-082,erythropoietin, Fujimycin (IUPAC name[3S-[3R*[E(1S*,3S*,4S*)],4S*,5R*,8S*,9E,12R*,14R*,15S*,16R*,18S*,19S*,26aR*]]-5,6,8,11,12,13,14,15,16,17,18,19,24,25,26,26a-hexadecahydro-5,19-dihydroxy-3-[2-(4-hydroxy-3-methoxycyclohexyl)-1-methylethenyl]-14,16-dimethoxy-4,10,12,18-tetramethyl-8-(2-propenyl)-15,19-epoxy-3H-pyrido[2,1-c][1,4]oxaazacyclotricosine-1,7,20,21(4H,23H)-tetrone,monohydrate, also known as FK-506 and any combinations thereof.

Suitable non-limiting examples of modulators of lipid formation,storage, and release pathways are apolipoprotein; statins; and anycombinations thereof.

Suitable non-limiting of blood flow modulators are adenosine receptormodulators such as ATL-146e.

In different embodiments of the invention, the at least one bioactiveagent is selected from the group consisting of thalidomide, bevacizumab,marimastat, α-IFN, MMP inhibitors, Neovastat (AE-941) Rh endostatin,netrins, NOGO-derived proteins, myelin-derived proteins,oligodendrocytes-derived proteins, botulinum toxin, anesthetics,Substance P receptor (NK1) antagonists, opioids, α-Adrenoceptoragonists, cannabinoids, cholinergic receptor agonists, GABA agonists,glutamate receptor antagonists,[N-(4-Hydroxy-3-methoxyphenyl)methyl]-5Z,8Z,11Z,14Z-eicosatetraenamide](Arvanil),8-Methyl-N-vanillyl-trans-6-nonenamide (Capsaicin),N-[2-(4-Chlorophenyl)ethyl]-1,3,4,5-tetrahydro-7,8-dihydroxy-2H-2-benzazepine-2-carbothioamide(Capsazepine), 8-Methyl-N-vanillylnonanamide (Dihydrocapsaicin),6,7-Deepoxy-6,7-didehydro-5-deoxy-21-dephenyl-21-(phenylmethyl)-daphnetoxin,20-(4-hydroxy-5-iodo-3-methoxybenzeneacetate) (5′-Iodoresiniferatoxin);(+)-Isovelleral, N-Vannilyloleoylamide (Olvanil), Phorbol12,13-dinonanoate 20-homovanillate, Resiniferatoxin;N-(3-Methoxyphenyl)-4-chlorocinnamide (SB-366791),2,3,4-Trihydroxy-6-methyl-5-[(2E,6E)-3,7,11-trimethyl-2,6,10-dodecatrienyl]benzaldehyde(Scutigeral),6,7-Deepoxy-6,7-didehydro-5-deoxy-21-dephenyl-21-(phenylmethyl)-20-(4-hydroxybenzeneacetate)daphnetoxin(Tinyatoxin), capsaicin synthetics, capsaicin derivatives, antibodiestargeting vanilloid receptors, capsaicin, capsaicin derivatives,capsaicin synthetics, piperine, mustard oil, eugenol, NGF antagonists,anecortave acetate, triamcinolone acetonide, combretastatin, ananti-angiogenic steroid, an angiostatic steroid, pegaptanib,ranibizumab, minocyclin, fluorocitrate and any combination thereof.

Vascular Indications

Certain aspects of the present invention provide for treatment ofvascular indications, such as for example, hypotension, atheroscleroticlesions, vulnerable plaque, and acute myocardial infarct.

Inflammation is now known to be a major driving force underlying theinitiation of coronary plaques leading among others, to injured,dysfunctional and leaky endothelium at the area of the lesion. Oneaspect of the present invention provides for biosealing of theatherosclerotic lesions. This aspect of the present invention may alsoprovides for a combination of a biosealing agent and anti-inflammatoryagent.

Exemplary pro-inflammatory molecules include cytokines, chemokines,neuropeptides, bradykinin, histamine and prostaglandins. Suitable activeingredients may include steroids, nonsteroidal anti-inflammatory drugs,COX inhibitors, modulators of TNF-alpha or IL-1 cytokine levels orreceptors.

In addition, potential benefit may arise from biosealing protection fromoxidized-lipids deposition at the vessel wall/plaques area.

Vulnerable plaque (advanced and rapture prone atherosclerotic lesionsand ruptured plaques) are characterized by denuded endothelium withinflammatory elements as a nidus for platelet-fibrin clumping. Oneaspect of the present invention provides for biosealing of the plaquearea to reduce thrombogenicity (platelets deposition).

Myocardial damage after Acute myocardial infarction (“aMI”) occurs atlarge due to the myocardial ischemia reperfusion (IR) injury. Thisinjury is attributed to the extensive cell death within the myocardialtissue, most likely via activation of programmed cell death relatedamong other parameters to oxidative stress due to reperfusion. Oneaspect of the present invention provides for biosealing during and afteraMI to reduce injury and oxidation related damage.

In humans and in animal models, spine injuries especially at highthoracic and cervical levels often result in hypotension which reducestissue perfusion and may impair functional recovery and orthostatictolerance. Hypotension can be evaluated by the measure of the meanarterial pressure at rest.

Autonomic dysreflexia is a common and potentially life threateningcondition associated with spine injury. Autonomic dysreflexia is asympathetic reflex characterized by large increases in blood pressure inresponse to a noxious stimulus below the level of injury; most commonlybladder or bowel distension. It can be evaluated by recording changes inthe mean arterial pressure and blood flow during induced episodes ofbladder or bowel distension.

Measure of mean blood vessels pressure, blood flow and characteristicsof cardiac rhythms can be used to monitor changes in cardiovascularfunctions.

EXAMPLES Example 1 Treatment with a Biomembrane Sealing Agent,Polyethylene Glycol or Peg, Reduced the Severity/Occurrence of ChronicPain Following Tissue Injury without Affecting Motor Functions or theSize of the Lesion

Animal Model of Chronic Pain

Wistar female rats weighing 200-250 grams received a controlledclip-compression injury at T4. This experimental model has beenpreviously described in details in Gris et al., 2004. Briefly, animalswere premedicated with diazepam (3.5 mg/kg, i.p.) and atropine (0.05mg/kg, s.c.) in order to facilitate a smooth induction of anesthesia by4% halothane and maintenance with 1.0-1.5% halothane. The T4 spinal cordsegment was exposed by dorsal laminectomy and a modified aneurysm clip,calibrated to 50 grams compression was passed extradurally around thecord and spring released for 60 seconds. Nerve roots were not disruptedduring the clip compression.

Treatment

Following injury, animals were placed in their home cage and dosing wasinitiated. Animals were treated with 0.5% saline or a PEG solutioncomposed of PEG3350 at 30% in 0.5% saline (custom made by AAIPharmaDevelopmental Services, Wilmington, N.C.). Saline and PEG solutions wereadministered by intravenous injections. Each animal received 2injections, the first one 15 minutes after injury and the secondinjection 6 hours later. Each injection delivered a single dose of 1g/kg for a total dose of 2 g/kg (body weight). There was 10-11animals/group. These studies were performed in a randomized and blindedfashion such as the solutions were sent to the Research Center inblindly labeled packages and the code was not revealed to the examinersbefore the end of the study.

Assessment of Development of Neuropathic Pain

Mechanical Allodynia: Animals were tested for the development ofneuropathic pain or mechanical allodynia before and up to 7 weekspost-injury. Neuropathic pain occurrence and severity was evaluated bythe response of the animal to a stimulus that is normally not painful orallodynia. Briefly, a modified Semmes-Weinstein monofilament (StoeltingCo, Wood Dale, Ill.) calibrated to generate a force of 15 mN was appliedto the dorsal trunk at dermatomes corresponding to spinal segmentsimmediately rostral to the lesion level (T1-T3). The monofilament wasapplied 10 times for 3 seconds, with each stimulus being separated by a5 second interval, and the number of avoidance responses out of apossible 10 were recorded. Avoidance responses were defined asflinching, escape, vocalization, or abnormal aggressive behaviors. Thescoring system used to monitor mechanical allodynia has been presentedin details in Gris et al., 2004. Mechanical allodynia testing wasconducted twice per week and the 2 tests were averaged for each animaland reported as a weekly pain score.

Thermal hyperalgesia: Animals were tested for the development ofneuropathic pain as measured by thermal hyperalgesia at 7 weekspost-injury. Neuropathic pain occurrence and severity was evaluated bythe level of response of the animal to a thermal stimulus that isnormally painful. Changes in sensitivity to thermal noxious stimuli wereevaluated by inserting the tail of the animal in hot water (50° C.) andby monitoring the time before the tail-withdrawal response (in second).

Assessment of Locomotor Recovery

Locomotor recovery was assessed by the 21-point Basso, Beatie andBresnahan (BBB) open field locomotor test (Basso et al., 1995), from day3-21 after injury. Locomotor function was evaluated by 2 blindedinvestigators at each testing period.

Assessment of Lesion Size

At the end of the behavorial study, animals were anesthetized with a 2:1ketamine/xylazine solution and perfused with a 4% formaldehyde solutionto fix the tissues. Spinal cords were removed, cryostat-sectionedtransversely at 20 μm and serially thaw-mounted on slides. One set ofcord sections was stained with Solochrome cyanin to detect myelin, andanother adjacent set of sections was immunoprocessed for neurofilament200 in order to identify axons.

Statistical Analysis

To evaluate the significance of difference between experimental groups,data were analyzed using an unpaired, two-tailed t statistical test withconfidence intervals of 95%.

Results

Treatment of injured animals with PEG had no effect on lesion size ormotor recovery relative to injured animals treated with saline.

Prior to injury, the allodynic pain score of the animals was equal tozero. The number of avoidance responses of the injured animals injectedwith saline increased progressively after injury to reach a mean painscore of 5+/−0.5 at week-7 post-injury consistent with the developmentof neuropathic pain. Treatment with PEG significantly (P<0.05) reducedthe severity/occurrence of neuropathic pain to 3.5+/−0.5 at week 7.Significant reduction of neuropathic pain (P<0.05) was seen in PEGtreated animals as early as week-4 post-injury with a pain score of2.9+/−0.4 relative to a pain score of 4.5+/−0.5 in the injured grouptreated with saline.

In general, non-injured rats have a tail-flick latency response of10.1±0.7 seconds. At seven weeks post-injury, injured animals treatedwith saline showed an hyperalgesic response corresponding to tail-flicklatency of 3.7+/−0.5 seconds. Hyperalgesia was significantly (p<0.05)reduced in PEG treated animals with an increased latency response of6.0+/−0.8 seconds relative to the injured group treated with saline.

Example 2 Treatment with a Biomembrane Sealing Agent, PolyethyleneGlycol or Peg Reduced Severity of Acute Pain in a Model of AcuteInflammation Induced by a Cuteneous Chemical Irritant

Animal Model of Acute Pain and Inflammation

The carrageenan model (Iadarola et al., 1988) was used to induce hindpaw acute inflammation. Male Sprague-Dawley (258±2.2 g) wereanesthetized with isoflurane, and 50 μL of 2% of the chemical irritantλ-carrageenan (w/v; Sigma, catalog #C-3889, lot #122K1444) was injectedintradermally into the left hind paw using a 1 cc syringe fitted with a27 g needle. For the sham group, 50 μL of 0.9% saline was injected intothe hind paw in an identical manner.

Treatment

Animals were treated with 0.5% saline or a PEG solution composed ofPEG3350 at 30% in 0.5% saline (custom made by AAIPharma DevelopmentalServices, Wilmington, NC). Saline and PEG solutions were administered byintravenous injections. Each animal received 2 injections, the first 15minutes prior to carrageenan injection and the second one 6 hours aftercarrageenan injection. Each injection delivered a single dose of 1 g/kgfor a total dose of 2 g/kg (body weight). There was 5-6 animals/group.These studies were performed in a randomized and blinded fashion such asthe solutions were sent to the Research Center in blindly labeledpackages.

Assessment of Pain

Ten hours following carrageenan injection into the left paw, the samepaw was tested for mechanical allodynia. Baseline and post-treatmentvalues for non-noxious mechanical sensitivity were evaluated using 8Semmes-Weinstein filaments (Stoelting, Wood Dale, Ill., USA) withvarying stiffness (0.4, 0.7, 1.2, 2.0, 3.6, 5.5, 8.5, and 15 g)according to the up-down method (Chaplan et al., 1994). Animals wereplaced on a perforated metallic platform and allowed to acclimate totheir surroundings for a minimum of 30 minutes before testing.

Assessment of Hind Paw Edema:

Hind paw edema was assessed by measuring paw volume using waterdisplacement. At each test time point, rats were gently restrained, andthe hind paws were individually immersed in water up to the hairlineabove the ankle. The water displaced was measured to the nearest 0.1 ml(cc³). The mean and standard error of the mean (SEM) were determined foreach treatment group.

Statistical Analysis:

To evaluate the significance of difference between experimental groups,data were analyzed using an unpaired, two-tailed t statistical test withconfidence intervals of 95%.

Results

After 10 hours, the mean pain score in the carrageenan-saline group was4.2+/−0.6 and significantly lower (p<0.001) than the mean pain score ofthe sham (saline-saline) animals evaluated at 13.1+/−1.0. In thiscarrageenan-paradigm, treatment with PEG significantly improved the painscore to 9.9+/−1.1 (p=0.0011) relative to the carrageenan-saline group.Paw edema or paw volume of the paw that received the carrageenaninjection was also decreased by 37% in PEG treated group relative tosaline treated animals.

Example 3 Biomembrane Sealing Agent, Polyethylene Glycol, can RestoreMean Arterial Pressure After Tissue Injury But Did Not Affect NeuronalControl of Autonomic Dysreflexia

Animal Model Affected by Decreased Mean Arterial Pressure and AutonomicDysreflexia

Wistar female rats weighing 200-250 grams received a controlledclip-compression injury at T4. This experimental model has beenpreviously described in details in Gris et al., 2004. Briefly, animalswere premedicated with diazepam (3.5 mg/kg, i.p.) and atropine (0.05mg/kg, s.c.) in order to facilitate a smooth induction of anesthesia by4% halothane and maintenance with 1.0-1.5% halothane. The T4 spinal cordsegment was exposed by dorsal laminectomy and a modified aneurysm clip,calibrated to 50 grams compression was passed extradurally around thecord and spring released for 60 seconds. Nerve roots were not disruptedduring the clip compression.

Treatment

Following SCI, animals were placed in their home cage and dosing wasinitiated. Animals were treated with 0.5% saline or a PEG solutioncomposed of PEG3350 at 30% in 0.5% saline (custom made by AAIPharmaDevelopmental Services, Wilmington, N.C.). Saline and PEG solutions wereadministered by intravenous injections.

Each animal received 2 injections, the first one 15 minutes after injuryand the second injection 6 hours later. Each injection delivered asingle dose of 0.3 g/kg for a total dose of 0.6 g/kg (body weight).There was 10-11 animals/group. These studies were performed in arandomized and blinded fashion such as the solutions were sent to theResearch Center in blindly labeled packages and the code was notrevealed to the examiners before the end of the study.

Assessment of Cardiovascular Functions

Mean arterial pressure value at rest and variation of mean arterialpressure during assessment of autonomic dysreflexia were acquired andanalysed using Powerlab software (AD Instruments, Mountain View,Calif.). Autonomic dysreflexia is a sympathetic reflex characterized bylarge increases in blood pressure in response to a noxious stimulusbelow the level of injury; most commonly bladder or bowel distension. At6-7 week post-injury the left carotid artery of each animal wascannulated under halothane anesthesia. The severity of autonomicdysreflexia was then tested in each rat approximately 2 or 3 days aftercannulation by measuring the increase in mean arterial pressure (MAP)during colon distension with a balloon-tipped catheter inflated with 2.5ml of air (Weaver et al., 2001). Blood pressure was continuouslymonitored until a true resting baseline was established, and then theballoon was inflated over 15 sec, with the inflation maintained for 1min. The MAP was averaged over the entire minute of inflation todetermine the dysreflexic response, and two trials were conducted foreach animal and averaged. The inflation of the balloon with 2.5 ml ofair generates a colon distension similar to that during the passing of alarge fecal bolus and is only slightly noxious to a rat with an intactspinal cord (Marsh et al., 2004).

Results

Tissue injuries such as high thoracic and cervical spinal cord injuryoften result in hypotension. At 7 weeks post-injury, animals treated PEGshowed a significant increase (P<0.05) in resting mean arterial pressurewith an average value of 115.0+/−3.6 relative to 105.9+/−1.0 mmHgmeasured in injured animals treated with saline. However, neuronalfunctions responsible for regulation of autonomic dysreflexia was notaffected treatment with PEG suggesting that the biomembrane sealingagent may have had a direct effect on restoring the integrity of bloodvessels following tissue injury rather than a general effect on neuronalactivity.

Example 4 Biomembrane Sealing Agent, Polyethylene Glycol, Accumulates inand Around Damaged Blood Vessels

Animal Model of Tissue Injury and Biodistribution of Active BiomembraneSealing Agent

Male Sprague Dawley rats underwent a moderate T9/10 contusion (1.5 mmdisplacement) using the Ohio State University Impactor. Immediatelyafter injury, the jugular vein was exposed, and 500 mg (250 mg/mlsolution) of biotinylated PEG3000 (Biotin-PEG, custom made By NecktarTherapeutics, Huntsville, Ala.) was injected into the vein. The animalswere then sacrificed 24 hours post-injury, and a 1.5 cm segment ofspinal cord harvested freshly (ie. no fixation). The cord was cutlongiditudinally, and immunohistochemistry was performed using anantibody to rat endothelial cell antigen (RECA-1) to visualize the bloodvessels; Cy3 conjugated streptavidin was used to visualize thebiotin-labeled PEG.

Results

The analysis of this spinal cord revealed a preferential accumulation ofthe biomembrane sealing agent at the site of injury. Super-imposedimages showed co-localization of the biomembrane sealing agent andendothelial cell signals. In most cases, the biomembrane sealing agentappeared to surround the damaged blood vessels found in the injury site.

Conclusion

In the present invention, applicants described the ability of a class ofagent, referred to as biomembrane sealing agents, to reduce acute painand inflammation as well as the development of chronic pain followingtissue injury. Applicants demonstrated the ability of this class ofagents referred to as “biomembrane” to reduce the severity ofhyperalgesia and allodynia following tissue injury. The dramaticreduction of chronic pain development after neuronal injury was notassociated with significant changes in motor recovery or size of thelesion. These results emphasize the delineation between recovery ofneuronal function in general and development of a pathological conditionsuch as chronic pain. Applicants also showed the ability of thebiomembrane sealing agent to accumulate all around damaged blood vesselsand help restoring normal mean arterial pressure and blood flow ininjured animals.

Although the invention herein has been described with reference toparticular embodiments, it is to be understood that these embodimentsare merely illustrative of the principles and applications of thepresent invention. It is therefore to be understood that numerousmodifications may be made to the illustrative embodiments and that otherarrangements may be devised without departing from the spirit and scopeof the present invention as defined by the following claims.

All publications cited in the specification, both patent publicationsand non-patent publications, are indicative of the level of skill ofthose skilled in the art to which this invention pertains. All thesepublications are herein fully incorporated by reference to the sameextent as if each individual publication were specifically andindividually indicated as being incorporated by reference.

1. A composition for treating or preventing pain consisting of at leastone biomembrane sealing agent.
 2. The composition of claim 1 wherein theat least one biomembrane sealing agent is selected from the groupconsisting of polyalkylene glycol, polyalkylene oxide, a surfactant andamphipathic polymer.
 3. The composition of claim 1 wherein the at leastone biomembrane sealing agent is selected from the group consisting ofpoly(ethylene glycol), a block copolymer containing a polyalkyleneglycol, triblock containing a polyalkylene glycol, a block copolymercontaining a polyalkylene oxide, triblock containing a polyalkyleneoxide, polyvinyl alcohol, polyvinyl pyrrolidone, dextrans, poloxamine,pluronic polyols, dimethylsulfoxide, hydroxyethylstarch, sodiumcarboxymethyl cellulose and combinations thereof.
 4. The composition ofclaim 1 wherein the at least one biomembrane sealing agent ispoly(ethylene glycol).
 5. The composition of claim 1 wherein the atleast one biomembrane sealing agent is poly(ethylene glycol) having amolecular weight of between about 1400 and about 20000 Da.
 6. A methodof treating pain, the method comprising delivering to a subject in needthereof a therapeutically effective amount of at least one biomembranesealing agent, wherein the at least one biomembrane sealing agent isdelivered in an injectable composition, wherein further the at least onebiomembrane sealing agent comprises more than about 10% of theinjectable composition.
 7. The method of claim 6 wherein the at leastone biomembrane sealing agent is selected from the group consisting ofpolyoxyethylenes, polyalkylene glycol, poly(ethylene glycol), polyvinylalcohol, pluronics, poloxamers, methyl cellulose, sodium carboxylmethylcellulose, hydroxyethyl starch, polyvinyl pyrrolidine, dextrans,poloxamer P-188, and any combination thereof.
 8. The method of claim 6wherein the therapeutically effective amount of at least one biomembranesealing agent and is delivered by a method selected from the groupconsisting of an intravenous administration, an intramuscularadministration, an intrathecal administration, a subcutaneousadministration, an epidural administration, a parenteral administration,an intra-articular administration, a direct application or depositiononto or adjacent to a site of the pathological condition, and anycombinations thereof.
 9. The method of claim 8 wherein the subject issuffering from diabetic neuropathy, alcoholic neuropathies,postherapeutic neuralgia, Complex Regional Pain Syndrome, stroke,traumatic brain injury, spinal cord injury, sciatica, carpal tunnelsyndrome, phantom limb pain, multiple sclerosis, arthritis and otherjoint diseases, pain from post-surgical or other invasive treatments, ortraumatic tissue injury
 10. A method of preventing pain, the methodcomprising delivering to a subject post-injury or post-surgery, butbefore the onset of acute or chronic pain a therapeutically effectiveamount of at least one biomembrane sealing agent wherein the at leastone biomembrane sealing agent is delivered in an injectable composition,wherein further the at least one biomembrane sealing agent comprisesmore than about 10% of the injectable composition.
 11. A method forreducing the severity of the symptoms after onset of acute or chronicpain in a subject comprising administering to a subject suffering fromthe onset of pain an effective amount of a biomembrane sealing agent.12. The method of claim 11 wherein the subject is suffering fromdiabetic neuropathy, alcoholic neuropathies, postherapeutic neuralgia,Complex Regional Pain Syndrome, stroke, traumatic brain injury, spinalcord injury, sciatica, carpal tunnel syndrome, phantom limb pain,multiple sclerosis, arthritis and other joint diseases, pain frompost-surgical or other invasive treatments, or traumatic tissue injury.